It has been well known that dye images are produced by subjecting a light-sensitive silver halide color photographic material to imagewise exposure to effect color development, whereby an oxidized product of an aromatic primary amine type color developing agent couples with a coupler to form dyes including, for example, indophenol, indoaniline, indamine, azomethine, phenoxadine, phenadine and other dyes similar to these. In such a photographic system, generally employed is a color reproduction system utilizing the subtractive color process, in which used is a color photographic material comprising blue-sensitive, green-sensitive and red-sensitive silver halide emulsion layers containing couplers each having the relationship of complementary color, namely, couplers which color-develop in yellow, magenta and cyan, respectively.
The coupler used for formation of yellow color images includes, for example, acetoanilide type couplers, and, as the coupler for formation of magenta color images, for example, pyrazolone, pyrazolobenzimidazole, pyrazolotriazole or indazolone type couplers are known, and further, as the coupler for formation of cyan color images, for example, phenol or naphthol type couplers are generally used.
The dye images thus obtained are desired not to undergo any color change or color-fading even when exposed to light for a long period of time or preserved under the conditions of high temperature and high humidity. Also desired are those in which non-image portions of a color photographic material may not yellow by light, moisture or heat.
However, in the case of magenta couplers, yellow stain (or Y-stain) by light, at a non-image portion and color-fading by light, at a dye image portion are very largely caused as compared with those in the case of yellow couplers or cyan couplers, to often raise problems.
The coupler widely used for formation of magenta dye includes, for example, 1,2-pyrazol-5-on type couplers. It has been a serious problem that the magenta couplers of 1,2-pyrazol-5-on type have a secondary absorption at the vicinity of 430 nm in addition to a primary absorption at the vicinity of 550 nm, and therefore various studies have been made to solve such a problem.
A magenta coupler having an anilino group at the 3-position of the 1,2-pyrazol-5-on type coupler, which is small in the above-mentioned secondary absorption, is useful for obtaining, in particular, a color image for printing. This art is disclosed, for example, in U.S. Pat. No. 2,343,703, British Pat. No. 1,059,994, etc.
However, the above magenta couplers have a disadvantage that they are extremely poor in the image stability, in particular, the fastness to light of dye images, to suffer from Y-stain at a non-image portion.
As a means for decreasing the secondary absorption at the vicinity of 430 nm of the above magenta coupler, there have been proposed magenta couplers including, for example, pyrazolobenzimidazoles disclosed in British Pat. No. 1,047,612, indazolones disclosed in U.S. Pat. No. 3,770,447, and pyrazolotriazoles disclosed in U.S. Pat. No. 3,725,067, British Pat. Nos. 1,252,418 and 1,334,515, Japanese Unexamined Patent Publications Nos. 162548/1984 and 171956/1984, etc. The dyes formed through these couplers shows extremely smaller secondary absorption at the vicinity of 430 nm than the dyes formed through the 1,2-pyrazol-5-on type coupler do, and thus, they are desirable from the viewpoint of the color reproducibility, and also they are advantageous in that they are desirably very little liable to generation of Y-stain at a non-image portion against light, heat and humidity.
However, in general, the azomethine dye to be formed through the magenta couplers of pyrazolotriazole type have very low fastness to light to seriously damage the performances of a color photographic material, in particular, a color photographic material for print, and therefore have not put into practical use in color photographic materials for print.
Japanese Unexamined Patent Publication also proposes a technique for improving the fastness to light of a magenta dye image obtained from 1H-pyrazolo-[3,2-C]-s-triazole type magenta coupler by using 1H-pyrazolo-[3,2-C]-s-triazole type magenta coupler in combination with a phenol type compound or a phenol ether type compound. However, even the above technique can not be said to be sufficient for preventing the color-fading of the above magenta dye image against light, and, moreover, has been recognized to have almost no capability to prevent the color-fading by light.
The above pyrazolotriazole type magenta coupler has also a tendency that the gradation may become soft particularly at the toe portion in the Density-Log Exposure Curve, as compared with the conventional 1,2-pyrazol-5-on type couplers.
For this reason, when applied in a color photographic material, the balance in the gradation at a red-sensitive layer, a green-sensitive layer and a blue-sensitive layer may be lost to make the magenta color liable to be conspicuous at the highlight portion. For this reason, in photographic materials for color print, the so-called highlight pink phenomenon may occur, in which, for example, the sky and the cloud look pinky, and also the snow looks not white but pinky. Eyes of a human can distinguish such delicate changes particularly at a low density portion and judge the finish of a color print to be undesirable.
Accordingly, in designing a color photographic material, enormous efforts are wasted to take the balance in the three layers particularly at the low density portion.
Thus, the phenomenon that the toe portion is made to have soft gradation by the above pyrazolotriazole type magenta coupler may cause an extreme decrease in the value of goods due to the highlight pink tendency, to give a defect that can be not overly said to be fatal.
There have been hitherto made various studies on the method for controlling the gradation of light-sensitive silver halide photographic materials.
For example, the methods generally used may include a method in which the amount of silver halide to be applied is increased or decreased, the amount of couplers to be applied is increased or decreased, and the proportion of the amount of silver halide to be applied, to the amount of couplers to be applied is varied; a method in which two or more kinds of silver halide emulsions having different grain size and sensitized by different methods are mixed, as disclosed, for example, in Japanese Unexamined Patent Publications Nos. 71320/1975, 44016/1978, 78831/1981, 58137/1982, 150841/1982, 178235/1982, 14829/1973, etc.; further, as a method generally used, a method in which conditions and additives are selected in the manner that the toe portion can be made hard when silver halide grains are chemically sensitized or color sensitized; and still further, a method in which a water soluble rhodium salt is added when silver halide grains are formed, as disclosed, for example, in Japanese Unexamined Patent Publications Nos. 11029/1977 and 18310/1977, British Pat. No. 1,535,016, U.S. Pat. No. 3,448,709, etc.
In these methods, however, not only the gradation at the toe portion is made hard as intended, but also the gradation at the shoulder portion is made hard, or the gradation may be made soft during the preservation with time lapse, or other photographic performances, for example, sensitivity, fog, exposure characteristics, etc. may be adversely affected. Thus, in the present state, there has not been found in the conventional techniques any effective means such that the gradation only at the toe portion is made hard without any influence to other performances.
On the other hand, a surface active agent is generally used when magenta couplers are dispersed in a silver halide emulsion layer. However, the above pyrazolotriazole type magenta coupler has very poor dispersion stability to adversely affect the photographic performances.
Under such circumstances, it has been sought after to give a light-sensitive silver halide photographic material utilizing the above-mentioned excellent properties of the pyrazolotriazole type magenta coupler, having good dispersion stability of the magenta coupler, and moreover improved in the image stability, the toe portion gradation and the stain.